Geologists uncovered an unusual magnetic anomaly beneath the ground in Australia’s Northern Territory, whose shape strikingly resembles the continent itself. This structure mirrors Australia’s characteristic outlines: a widening in the center, a “protrusion” in the north, and two elongated sections in the east and west. The ScienceAlert portal reports on this.
The anomaly was detected during an aeromagnetic survey organized by governmental agencies. Small aircraft fitted with magnetometers flew over the area at 400-meter intervals, recording the slightest shifts in the magnetic field.
The new information allowed for the examination of the rocks’ so-called remnant magnetism. When rocks form, the magnetic minerals within them “record” the direction of the Earth’s magnetic field. Even after millions and billions of years, they retain this intelligence, despite the drift of magnetic poles and their periodic reversals.
The study’s authors note that magnetic data allows one to peer underground and better understand the features of the geological architecture. Australia has changed its position multiple times throughout its geological history due to tectonic processes, and the direction of the Earth’s magnetic field has also shifted. Therefore, interpreting such data demands significant expertise and experience.
Scientists established a link between the anomaly and ancient volcanic rocks older than 1.5 billion years. These layers alternate with sandstones formed in shallow seas and river deltas. Subsequent tectonic forces deformed them, thus creating the structure whose contours coincidentally match the continent’s geometry.
The new map is the most detailed to date. The data has already been published in the open Geoscience Australia database. Researchers are confident it will be useful not only for refining the region’s geological history but also for prospecting potential mineral deposits.
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